The present invention relates to golf balls having integral temperature sensors. The temperature sensor comprises a stamp or mark that changes color at a predetermined temperature, allowing a golfer to determine the approximate temperature of a golf ball and hence its suitability for play. Knowing the temperature of a golf ball is useful in that it allows a golfer to determine when a golf ball is capable of delivering maximum performance when struck by a golf club.
Generally, golf balls are one of three types. A first type is a multi-piece wound ball wherein a vulcanized rubber thread is wound under tension around a solid or semi-solid core, and thereafter enclosed in a single or multi-layer covering of a tough, protective material. A second type of golf ball is a one-piece ball formed from a solid mass of a resilient material that has been cured to develop the necessary degree of hardness to provide utility. One-piece molded balls do not have a second enclosing cover. A third type of ball is a multi-piece non-wound ball that includes a liquid, gel or solid core of one or more layers and a cover having one or more layers formed over the core.
Attempts to improve and/or optimize performance characteristics in golf balls are typically directed toward achieving better feel when the ball is struck with a golf club, and also allowing for increased or optimum distance while at the same time adhering to the rules set forth by the United States Golf Association (U.S.G.A.) regarding the physical characteristics and performance properties of golf balls. These rules specify that the weight of a golf ball shall not be greater than 1.620 ounces, the diameter of the ball shall not be less than 1.680 inches and the velocity of the ball shall not be greater than 255 feet per second (250 feet per second with a 2% tolerance level). The U.S.G.A. rules also specify that the overall distance a golf ball should travel shall not cover an average distance (in carry and roll) greater then 280 yards, plus a 6% tolerance level (296.8 yards total).
Over the years, attempts to improve characteristics such as feel and durability have centered around the materials used to form the various layers of a golf ball. Improvements in spin and distance characteristics are usually directed toward the actual construction and physical makeup of the golf ball. The use of one or more intermediate layers between a core and a cover layer to achieve such improvements is known in the art. The thickness and/or material hardness of each layer may also be varied in order to achieve a desired property.
In general, there is a natural transfer of energy that occurs within a golf ball when the ball is struck by a golf club. Energy is transferred from the club face to the golf ball cover, and then subsequently transferred through each layer beneath the cover. In solid non-wound golf balls employing spherical layers, energy transfer is generally a function of the thickness and material composition of a given layer. Therefore, varying either the thickness of a given layer and/or the material from which a layer is made affects the efficiency of energy transfer occurring within a golf ball and consequently affects the overall performance characteristics of that ball.
In both the wound and solid multi-layer golf balls, covers are placed around the preformed cores by techniques such as injection molding, compression molding, casting etc. When the cover is placed on the core, dimples are formed in the outer surface of the cover. This invention is concerned with the cover of a golf ball.
There exists a need for a golf ball design that assists a golfer in determining the approximate temperature of a golf ball and the ball""s suitability for play in a given set of weather conditions. Knowing the ball temperature allows a golfer to determine when the ball is capable of delivering maximum performance characteristics, such as spin and overall distance.
Golf balls having surfaces that incorporate dyes that change color due to an environmental change are known in the prior art. In this regard U.S. Pat. Nos. 5,938,544 and 5,823,891 to Winskowicz disclose golf balls which incorporate microencapsulated dyes in the surface thereof. These dyes change color upon prolonged exposure to water. The invention of these patents is useful for indicating when a golf ball becomes a xe2x80x9cwater ballxe2x80x9d as a result of a prolonged immersion in water. The dyes in question change color upon immersion and remain colored; they do not revert back to their original color.
Thermochromic materials have been incorporated into the face of a golf club for purposes of indicating the point of impact between a golf ball and a golf club face. See, for example, U.S. Pat. No. 5,597,361 to Hope, and U.S. Pat. No. 5,805,245 to Davis, which discloses the use of thermochromic liquid crystals to indicate temperatures over different ranges. Similarly U.S. Pat. No. 5,394,824 to Johnson Jr. discloses the use of thermochromic dyes to indicate the point of impact of a tennis ball with a tennis court. Finally, the incorporation of thermochromic dyes into printing inks is disclosed in U.S. Pat. No. 4,717,710 to Shimizu et al.
None of the patents discussed above discloses the use of a layer of a thermochromic material on the surface of a golf ball for purposes of indicating the temperature of said golf ball.
The present invention relates to new and improved golf balls that overcome the above referenced problems. In this regard, the present invention is directed to golf balls having a temperature indicating mechanism that indicates when a golf ball is at the optimum temperature for play.
In a first aspect, the present invention is directed to a golf ball comprising a core and a cover. The cover on its surface incorporates a section comprising a thermochromic material. The thermochromic material is capable of indicating whether the golf ball is above or below a predetermined temperature. The thermochromic section may be printed on the surface of the golf ball. The thermochromic material is selected from the group consisting of cholesteric liquid crystals and leuco dye systems.
In another aspect, the present invention is directed to a golf ball comprising a core and a cover. The cover incorporates on its surface an indicia that is covered with a thermochromic section. At a predetermined temperature, the thermochromic section becomes clear or translucent, thus allowing the observation of the indicia. The indicia may be a color, a readable word, a logo, or any other suitable indication that the golf ball is suitable for play. The thermochromic material is selected from the group consisting of cholesteric liquid crystals and leuco dye systems.